1. Field of the Invention
The present invention relates to an optically active novel compound and intermediate products thereof, and a process for the manufacture of same.
2. Description of the Related Art
Vitamin E is a methylated derivative of a tocopherol, and includes eight kinds of naturally occurring compounds, i.e., .alpha.-, .beta.-, .gamma.-, and .delta.-tocopherols, and .alpha.-, .beta.-, .gamma.-, and .delta.-tocotrienols. Although tocopherols and tocotrienols include d-form, 1-form or dl-form optical isomers, naturally occurring compounds showing optical activities have d-form. Synthesized tocopherols are generally prepared in the form of a diastereomer, and it is known that a chirality of the carbon atom of the 2-position in the chroman ring has a considerable affect on the physiological activities of tocopherols.
A method of synthesizing optically active tocopherols from optically active starting materials is described in, for example, N. Cohen, et al, Journal of the American Chemical Society, 101:22, Oct. 24, 1979, 6710-6716. In the method of Cohen, et al, an optically active desired .alpha.-tocopherol is obtained by using an optically active benzopyran derivative as a starting material, to form an optically active chroman-2-methanol derivative, and then performing a Wittig coupling of the chroman derivative to form the final .alpha.-tocopherol while retaining the chirality of the starting material. In this method, however, a resolution process is required to obtain the optically active starting material, and a poisonous hydrocyanic acid must be used during the course of the synthesis process.